Probiotic label amounts and strain identity: specifications that hold to the end of shelf life
Set the declared amount, the identity specification for each component and the stability plan together, so the label still holds when the product is sampled.
In Short
- Supplement Facts amounts are by weight.
- Each component needs an identity spec.
- Plan counts to last the shelf life.
The Dietary Supplement Operations Guide
What the label says. What the batch proves.
- The rules and who decides
- Specification to finished batch
- Test, review, investigate
We ask for your name and email so we can handle this request. The full guide then opens on this site, ready to translate, print or save. Privacy policy. Practical orientation, not legal advice; your quality unit decides which rules apply.
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The Dietary Supplement Operations Guide
What the label says. What the batch proves.
A probiotic label states an amount, and the product has to meet it when it is sampled, not only on the day it was made. This guide reads what the regulations say about declaring the amount, specifying the identity of each component and testing finished batches, and what FDA's draft guidance says about colony-forming units (CFU). Opened: eCFR 21 CFR 101.36 and 101.9(g) and Part 111 sections 111.70 and 111.75, up to date as of 1 Oct 2026; and FDA's September 2018 Draft Guidance for Industry, Policy Regarding Quantitative Labeling of Dietary Supplements Containing Live Microbials (FDA web page and PDF). That guidance is marked Draft, Not for Implementation and Contains Nonbinding Recommendations. Not opened: the Federal Register notice and docket comments, any later FDA statement on the draft, compendial or ISO methods, and any rule outside the US. It is orientation, not legal advice. Sources checked 5 Oct 2026.
What 101.36 requires, and what the draft guidance says about CFU
Under 21 CFR 101.36(b)(3), dietary ingredients without a Reference Daily Intake are listed by common or usual name, with the quantitative amount by weight per serving. The regulation does not mention CFU, and FDA's 2018 draft guidance confirms that inside Supplement Facts these ingredients can be quantified only by weight.
Worked Example: Label Line for Capsule PB-310
| Field | Entry | Source |
|---|---|---|
| Name | Lactiplantibacillus plantarum PB-07 | 101.36(b)(3)(i) |
| Amount per serving | 25 mg | 101.36(b)(3)(ii) |
| CFU figure (optional) | Only in addition to weight, if every draft condition is met | FDA 2018 draft guidance (nonbinding) |
- Name
- Entry
- Lactiplantibacillus plantarum PB-07
- Source
- 101.36(b)(3)(i)
- Amount per serving
- Entry
- 25 mg
- Source
- 101.36(b)(3)(ii)
- CFU figure (optional)
- Entry
- Only in addition to weight, if every draft condition is met
- Source
- FDA 2018 draft guidance (nonbinding)
More on what 101.36 requires, and what the draft guidance says about CFU
The draft says FDA intends to exercise enforcement discretion for a CFU figure in Supplement Facts in addition to weight, never instead of it, and only if listed conditions are met. It is a draft, not for implementation and nonbinding. Outside Supplement Facts, the draft says CFU may appear if not false or misleading, citing 101.13(i)(3).
Compliance is judged when the product is sampled
101.36(f)(1) says compliance is determined using the 101.9(g) method: a composite of 12 subsamples or 10 percent of packages, whichever is smaller, from a lot. The class I and class II criteria in 101.9(g)(3) and (g)(4) also apply to other dietary ingredients.
Which compliance class? (simplified 101.9(g))
Pick how the culture is present.
- Amount at least equal to the label value.
- 101.9(g)(3)(i) and (g)(4)(i).
More on compliance is judged when the product is sampled
For a class I (added) nutrient, the amount must be at least equal to the label value; for class II (naturally occurring), at least 80 percent. The draft guidance points to these same sections for minimum quantity throughout shelf life. Which class your regulatory team applies is a recorded decision. Counts that fall during storage are measured against the label, so the plan has to cover the whole claimed shelf life.
Component identity is a specification
21 CFR 111.70(b)(1) requires an identity specification for each component you use. For components that are dietary ingredients, 111.75(a)(1)(i) requires at least one appropriate test or examination to verify identity before use, unless FDA grants the petition exemption described in 111.75(a)(1)(ii).
More on component identity is a specification
Neither section names a method for probiotics, and neither says that each strain in a supplier's multi-strain blend needs its own separate identity specification or test. Write down what identity means for each component, record which organisms or strains the component is specified to contain, then name the method that confirms the component's identity and who checks the result. A supplier's certificate does not replace the identity test for a dietary ingredient.
Finished Batch Specifications
111.70(e) requires specifications for the finished batch covering identity, purity, strength and composition, and limits on contamination that may adulterate the product. Under 111.75(c) you either test every finished batch for the specifications you select, or use a sound statistical sampling plan, and you must choose specifications that, if met, show the process produced product meeting all of them.
More on finished Batch Specifications
For a probiotic, strength usually means the count of each culture or the blend. Record which organisms or strains the finished product is specified to contain, which specifications are tested each batch, which are verified another way, and why.
Stability evidence, the draft's conditions and decisions
The Part 111 sections opened require specifications and verification but do not set a shelf-life study design. That design is yours: storage conditions, packaging, time points, method and acceptance limit against the declared weight.
Stability Record for Lot PB-310
More on stability evidence, the draft's conditions and decisions
If your team also chooses to show CFU in Supplement Facts relying on the draft guidance, record each listed condition: weight first, CFU clearly separate, plain wording, accurate and not misleading, live organisms only, blend order by weight, and the rest of the label compliant. Record results by lot and time point. When a point trends low, a person decides whether to change overage, packaging or expiry.
Questions
Can a probiotic label show CFU instead of weight?
Not instead of weight inside Supplement Facts: 101.36(b)(3) requires weight. FDA's 2018 draft guidance, which is nonbinding and not for implementation, describes intended enforcement discretion for CFU shown in addition to weight, only under its listed conditions.
When does the label amount have to be met?
Under 101.36(f)(1), compliance is judged by the 101.9(g) sampling and class criteria, which apply to product as sampled. Plan specifications and overage so counts meet the declared amount through the claimed shelf life.
Does Part 111 name a strain identification method?
No method is named in 111.70 or 111.75. You need an identity specification for each component and at least one appropriate identity test for each component that is a dietary ingredient, unless FDA grants the petition exemption in 111.75(a)(1)(ii).
Does V5 decide our overage or shelf life?
No. V5 records specifications, lot results and stability time points against each lot. Your quality and regulatory teams decide overage, shelf life and release.
Practical orientation, not legal advice. Rules differ by jurisdiction; your quality and compliance team decides what applies.
Keep reading
Supplement Stability Testing: Shelf-Life Dating Using ICH Q1 Principles
ASEAN Supplements Readiness: Singapore HSA and the Regional Hub
Australian Listed Medicines: What the Sponsor Certifies Under Section 26A
Brazil ANVISA Supplements: RDC 243/2018 Readiness Guide
Supplement Contract Manufacturing: Part 111 Duties and Quality Agreements
Cosmetic Stability and Preservative Efficacy (ISO 11930)